Flexible corrugated-metal wall.



W. M. FULTON. FLEXIBLE CORRUGATED METAL WALL.

APPLICATION FILED MAR. 4, 1907. v

Patented Aug. 9, 1910.

tions.

tit

on irnn s'rArrns PATENT OFFICE. WESTON in. FULTON, orqmoxvILLn,Tennessee, ASSIGNOR TO THE runrou oom- .PANY, or KNOXVILLE, rmmnssnn, Acom-onnrrouor MAINE.

FLEXIBLE CORRUGATED-METAL WALL.

. Specification of Letters Patent:

Patented Aug. 9, 1910.

To all whom it may concern:

Be it known that I, its'roN M. FULTON,

of. Knoxville, Tennessee, have invented a,

new and useful Improvement in Flexible Corrugated-Metal Walls, whichimproves ,ment is fully set forth in the following specification.

This invention relates to vibratory corrugated metal walls, particularlyof collaps ble and expansible vessels for confimn fluid under pressure,and to the method o making such walls, and it has for its primary objectto provide a metal corrugated wall which is very thin and flexible,while securing at the same time strength and durability to a markeddegree.

It is well known in the art of metal 'workally termed a grain in themetal. This grain is particularly noticeable in thinsheet metal, Whetherrolled from a billet or in the form of a drawn tube. Metal having thisgrainis also known to have a greater tensile strength along the grainthan across it; likewise resilience, durabilityand the co efficient ofexpansion of the metal are not the same along the grain as inotherdirec- Metal tubes made from drawn or rolled metal possess, therefore,this grain to a more or less marked degree, and its presence lendstensile strength to the tube 711 directions parallel to the grain. Inthe manufacture of flexible corrugated sheet metal walls for collapsibleand expansible vessels as heretofore practiced, the grain of the metalwhich was lengthwise of the uncorrugated tube'retainsthis direction inthe corrugated tube and therefore crosses the planes of the transversecorrugations substantially at right-angles thereto. If such a wallconfines a fluid under pressure, as in the case of a collapsible andexpansible vessel, the greatest strains in the metal at the bends whenthe corrugations are extended and collapsed, are not normalto the cor:

rugations, but are more or less displaced from a true normal directionand make more or less acute angles with the planes of the corrugations.As a result of thus shifting the working strains in the metal at thebends into a direction more or less across the grainwhere the tensilestrength of the metal is less than in the direction of the grain, theendurance of the flexible corrugated wall does not reach its maximum.

It is therefore the primary object of this invention to overcome thisobjection and to provide a .flexible corrugated wall and method ofmaking the same, whereby the grain of the metal may be so distributed inthe corrugations, particularly at the bends, as to afford the maximumstrength along lines of greatest strains, thereby giving to the wall agreater endurance, while retaining therein the desirable quality ofthinness and flexibility.

These, together with other objects, will more fully appear in thedetailed description and be pointed out in the claims.

The inventive idea involved is capable of expression in a variety ofways or methods of procedure, one of which, for the purpose oflllus'trating theinvention, is hereinafter specifically described, butis given solely for the purpose of illustrating the invention, and notfor the purpose of defining the llmlts thereof, reference being had tothe claims for this purpose.

In order that the invention may be more readily understood, reference ishad to the accompanying drawings, in which Figure l is a view inelevation of a cor rugated metal. Wall; Fig. 2 is a View of a portion ofthe Wall highly magnified; Figs. 3 and 9 are views showing rolled sheetmetal blanks; Figs. 4, 5, 10 and 11 are elevational views of .the cups;Figs. 6 and 7 areviews' showing the cup after being corrugated; and Fig.8 is a vertical sectional view of a die for forming the blank cup. I

In Fig. 2 I have shown anenlarged view of a portion R, T, U, V of theside wall of a collapsible and expansible corrugated metal vesselthewalls of which are-subject to in ternal fluidpressure, for thepurpose of indicating the direction of the strains to which the variousportions of the wall are subjected under such conditions.

Fluid pressure within the vessel will exert on lateral walls 1, 2, equaland opposite forces 3 .normal to their inner surfaces tending toseparate them. These lateral walls 1,

perspective 2 being unitedbythe curved portions, 5

constituting the bend of the corrugations,

this portion 4, 5 will be subjected to. a tensile strain in thedirection G-H. Furthermore, when the flexible wall is collapsed andexpanded, the curved portion 4, '5 will be the arrows 6, 7

Considering now any small unit of area I, J, K, L, on the curved portion4:, 5 of the wall joining lateral portions 1, 2, and fixing attentionupon any point 0 within this unit area, there are acting thereat twoequal and opposite forces which may be represented in magnitude anddirection by the lines 0 M, O-N, and two other equal and opposite"forces 0 P, O Q. The resultant or vector sum of any two forces, 0 M, OP, acting approximately at right angles to each other, is greater thaneither and is represente'd'by a line OJ. In like manner, the vector sumsO K, O L, and O I, are each greater than either of the forces 0 P, O N,O Q, and Q It is evident that the greatest strains sustained in thebends of a flexible collapsible and expansible wall intended to sustainfiuidpressure from within or from without, are along the lines L O J andI O K. What has here been stated in respect to the portions of the outercorrugations equally applies to curved portions of the innercorrugations. The metal along these lines, therefore, should beespeciall strong, and one of the main objects of tie present inventionis to secure this needed strength means of a sheet metal drawing presshile at the same time retaining thinness of the wall.

v The preferred method by which I secure the objects of my invention, Iwill now de.

scribe. A sheet of metal such as brass, cop per or steel is rolled froma billet in the usual way, the grain of the metal lying parallel withthe length of the sheet. A blank 8 is then out from the sheet, shown inFi 3 as circular, though it may assume ot er forms such as oval or thelike. The grain of themetal will then lie across the blank, as indicatedby lines f f f. This blank is now shaped into a deep cup 9, preferablyby avingsuitable drawing dies, diagrammatically indicated in Fig. 8. Bysuccessive drawings and occasional annealing of the metal, the cup canbe given any desired depth. In the act of drawing the cup the originalain of the metal 7, f, f, is shifted so as to he along lines which areparallel neither to the axis nor the radius of the cup, as indicated inFigs. 4 and 5, in which, Fig. a shows the direction of the grain in theside correspondingto the side 10 of blank 8, and-Fig. 5 shows thedirection taken by the grain corresponding to side 11 of blank 8.Another V i i Y im ortant result of the drawing 0 eration it resides inthe fact that the friction etween the metal and the drawing diestoughens and strengthens the metal in directions more ing the blank 15between the flange holder 13 and lower die 12, and more particularlythat resulting from drawing the blanks over the curved mm 17, producesin the -metal a result similar to that produced by passing the blankthrough pressure rolls transverse to the grain of the blank, therebystrengthening the metal in directions transverse to the original grain.This die-drawn cup is peculiarly fitted for the next step of my process,which consists in deeply corrugating its. walls by means of corrugat-inrolls or by any other suitable means capable of efiectin the purpose. InFigs. 6 and 7, I have d agrammatically illustrated the cup withcorrugations having their planes at right-angles to the axis of thecylinder, though they may be spiral in relation thereto. The lines 'f,f, (5, indicate the direction taken by the shifte grain along which themetal has been chiefly strengthened to resist the princi al bendingstrains. From what has prece ed, it will, however, be manifest that themetal has also been strengthened to a somewhat lesser extent, however,in lines transverseto f, f, f, due to the act of drawing the cup in thedie. The corrugat-ing rolls have also a tendencyv to still furthertoughen the metal in the circumferential direction of the corrugationsor across the general direction of the original grain, but it is to beunderstood that such toughening does not even approach that reduced bythe pressure rolls in rolling the s eet metal from the billet, and isfar less than that produced by the drawing of the cup.

The method above described results in producing a flexible corrugatedwall of superior endurance, whether the fluid pressure on the wall befrom within or without for the reason that the metal in the bends o thecorrugations has been strengthened along the lines of greatest strain byshift1n the original grain into these directions, an also by materiallystrengthening the metal along lines across the original grain. Theseresults, itwill also be noted, have been secured without sacrificing theadvanta es of thinness of wall and flexibility whici are very essentialin a metallic co lapsible and expansible vessel.

. It has been stated above that the act of die-drawing the cupstrengthens the metal across the original grain. The strength of thesheet metal may be developed in directions more or less across theoriginal grain by other means than that above described.

For example, I may pass the sheet metal once or twice between pressurerolls in the direction -of its breadth to thin the sheet somewhat,thereby materially increasing the tensile strength and. ductility in thedirec tion across the grain,- without materially decreasing the tensilestrength and ductility in the direction of the original grain. Byreference to Figs. 9, l0 and 11, this will be apparent. Fig. 9 shows adisk of metal in the form of a circular blank similar to that of Fig. 3,except that the sheet metal from which it was cut has been rolled onceor twiceat right-angles to the original grain. lhe heavy horizontallines f, f, f, represent the original'grain of the sheet metal indirection and tensile strength, and the broken I 1 lines 7', f, f, in asimilar manner represent the cross grain. 'lhis blank when drawn into acup as described above, has a distribution of ,the two grains asindicated in l igs. l0 and 11, in which the dotted lines f, 7", f,indicate the effect of the cross rolladillicult task.

iug. When this blank is formed into a corrugated wall, asshown in Figs.6 and 7, it will be readily seen from what has preceded that the tensilestrength in the metal of the bends has been increased along the lines ofgriaitest-strain, thereby securing in the bend the greatest endurancewhile retaining a thin wall. My process also strengthens the lateralportions of the corrugated Wall, as'I have amply demonstrated bysuitable tests. The metal sheet may also be cross-rolled to streugthen-the metal in directions other than the original grain, and thenbent into tubular shape so that the original grain would for suchprocess accomplishes a three-fold result of (1) strengthening the metalin directions other than the original grain without materially weakeningsaid gram; (2)

shifting the original grain at an angle to scribed in my Patent No.762,300, dated June 7 14, 1904, I may draw several tube walls togetherby placing several blanks in the die at one time, and then separatelycor'rugating each cup, which it will be found possesses all thecharacteristics of asingle die-drawn blank. 1

Before forming the corrugations, I may remove the end wall of the cup,thus leaving only the cylindrical wall, and I usually prefer to do so,and finally replace the bottom ivith a thicker wall.

What I'claim is:

1. A, vibratory corrugated tubular wall of metal having the grain of themetal in the bends of the corrugations directed in lines making acuteangles with the axis of the tubular wall.

2. A vibratory corrugated tubular wall of rolled sheet metal having thegrain of the 'n'ietal in the bends-of the corrugations directed in linesmaking acute angles w1th the axis of the tubular wall. it 3; A vibratorycorrugated tubular wall of metal for confining fluids under pressure,

having the tensile strength of the metal in the bends developed in linesmaking acute angles with the axis of the tubular wall to correspond withthe lines of greatest straln therein.

In testimony whereof I have signed this specification in the presence oftwo subscribing witnesses.

WESTON M. FULTON. l l/Vitnesses: a Y

E. J. S. HYATT, J. C. TYLER.

